In a manufacturing process of a semiconductor device, a wet etching processing or a cleaning processing is performed on a substrate such as, for example, a semiconductor wafer by supplying a chemical liquid to the substrate. After the chemical liquid processing, a rinse processing is performed on the substrate so as to remove the remaining chemical liquid and reaction products from the substrate. The rinse processing is generally performed by supplying a rinse liquid usually composed of deionized water (DIW) to the substrate. At this time, in a case where an electrostatic breakdown might occur in device components which have already been formed on the substrate, an aqueous solution having a conductivity such as, for example, carbon dioxide dissolved water formed by dissolving carbon dioxide in deionized water, for example, by bubbling, or dilute ammonia water formed by adding a small amount of ammonia to deionized water, may be used as the rinse liquid (see, e.g., Japanese Patent Laid-Open Publication No. 2004-273799).
In order to suppress adverse effects such as corrosion of the device components, the pH of the rinse liquid may be adjusted to a proper value in a range of pH 5 to 9. However, for example, the dilute ammonia water undergoes a considerable change in pH depending on a change in ammonia concentration when the pH is 9 or less. Therefore, it is difficult to adjust the dilute ammonia water to have a desired value which is pH 9 or less. Likewise, it is also difficult to adjust the carbon dioxide dissolved water to have a desired value which is pH 5 or more.